The Comparison Of Fruit Quality Of Apple Cultivars And Genetic Tendency Analysis Of Fruit Quality Characters In F₁ Progenies

Fruit quality parameters are important agronomic and economic traits for fruit trees. Improving fruit quality is an important part in apple cross-breeding. It is the base to select optimal parents and establish simple apple fruit quality evaluation system and understand the inheritance of fruit quality parameters for achieving apple breeding goal. So, a total of 15 fruit quality parameters and anatomy structure were determined for ten apple varieties such as Starkrimson, Qinguan, Fuji, and Pink Lady in this study in 2009 and 2010. Quality parameters included fruit weight, soluble solid content (SSC), fruit color, and titratable acidity. Data were analysed using principal component and cluster analyses method. Some combinations and their F₁ progenies were used to study genetic tendency of fruit characters. The results were as follows:1. The results comparing fruit parameters of apple cultivars were as follows: New Jonagold had heavy fruit weight and bright color lightness; Pink Lady had high fruit shape index, fruit firmness and Vitamin C, cutin membrane was thick and uneven. Red Gala had bright color and good fruit shape. Ralls had good fruit flavor, high content of Vitamin C, and light fruit weight. Fruit flesh texture of Qinguan was firm. Qinguan was resistant to squeeze with thick and even epidermal cell layers structure. Starkrimson had smooth surface and light fruit flavor. The quality of Fuji apple was good with high solid soluble content. Jonathan had small fruit size and smooth surface, the epidermal cell was even and evenly spaced. The fruit shape index of Huaguan was relatively high. Huaguan had large epidermal cell, uneven cutin membrane and the fruit appearance was not smooth.2. Four comprehensive evaluation indices were extracted by principal component analysis using 15 quality parameters, with an eigenvalue of over 1 and a cumulative contribution of 93.275%. The four indices represented the characteristics of the apple varieties. Four varieties were selected according to the principal component scores, these were Ralls, New Jonagold, Red Gala and Pink Lady. The five most important fruit quality parameters were fruit weight or fruit shape index, fruit firmness, SSC, titratable acidity and fruit colour according to cluster analysis. Principal component and cluster analyses readily separated and prioritized apple fruit quality parameters for evaluation and selection purposes.3. Fruit weight, fruit shape index and fruit color were studied using Qinguan, Fuji, Pink Lady and their progenies as materials. The inheritance transfer ability of fruit weight was lowest with a high variance coefficient. Fruit weight showed a reduced non-additive genetic effect and tended to have a degenerative character. For each combination the proportion of ultra-low parent was very high while the proportion of ultra-high parent was low. The variance coefficient of fruit shape was lowest and showed weak non-additive genetic effect. Most of the progenies fruit shape index tended to be the same as the parents. The offspring of reciprocal crossing of Qinguan and Fuji were mostly conical. The fruit shape index of offspring of Fuji×Pink Lady was high. The fruit color of offspring of the three red-colored parents materials was mainly red, there were six different kinds of red color for the offspring of Fuji×Pink Lady, mainly bright red and pink, there were eight for the offspring of reciprocal crossing of Qinguan and Fuji, purple red and mahogany red existed only in offspring of reciprocal crossing of Qinguan and Fuji.4. The study of SSC, titratable acid and fruit firmness were also conducted. The inheritance transfer ability of soluble solid content was high, there was additive genetic effect. The progenies of Qinguan×Fuji showed wide genetic variation. The inheritance transfer ability of titratable acid was high, coefficient of variation was high. It indicated Pink Lady was a good variety for inheriting high acidity content. The percentage of low acidity offspring was high using Qinguan as female parent. The average fruit firmness for progenies was obviously higher than the mid-parent value, the inheritance transfer ability was high. There was wide genetic variation in F₁ offspring for fruit firmness. Different from fruit weight, the proportion of ultra-high parent was high and ultra-low parent was low. It showed minus non-additive genetic effect.